I had a branch on a Pine tree in my back yard I had to cut off after a storm earlier this year, and I cut the branch into manageable pieces & stored in my shop to dry out figuring I could make something with it later. it's later, and I have cut a section of the branch into 3" x 1/2" beverage coasters to give as gifts this Christmas. Once I sand them down to a smooth surface, I am not sure what kind of a finish would be best not only to protect them, but also taking into consideration how some glasses will sweat on them. I want to give gifts that folks will actually use for years, not once or twice & then discard because of a watery mess or problem. Any suggestions?